High Availability Link for Overwhelmed Meshes - Project HALO. Stop the flood

[mikecarper]

Currently set path packets like DMs and Traces are like UDP. If you can make the mesh more like TCP for DMs and Traces using the echo to make sure the packet got to the next spot; using the neighbors list as a way to make sure it's actually a viable link I think that'd be very helpful with preventing a flood.

If packet is direct and not flood, and
next hop is in the neighbors list, and
the next hop is SNR -2.5 or better (+5 SNR from the floor which is -7.5 for USA), and
the echo was not heard after X ms, send that packet again.